Device to device (D2D) communication is being studied in communication standard groups to enable data communication services between user equipments (UEs). During the D2D communication, a transmitting D2D UE can transmit data packets to a group of D2D UEs or broadcast control/data packets to all the D2D UEs or send unicast control/data packets to a specific D2D UE. D2D communication between the transmitter UE and receiver UEs is connectionless in nature, i.e., neither connection setup nor control messages are exchanged between the transmitter UE and the receiver UEs before the transmitter UE starts transmitting the control/data packets. During the transmission, the transmitter UE includes the source identity (ID) and the destination ID in the data packets. The source ID is set to the UE ID of the transmitter, while the destination ID is the intended recipient of the transmitted packet. The destination ID indicates whether the packet is a broadcast packet or a unicast packet or a packet intended for a group.
For group cast communication, the D2D UE can be member of one or more groups. In order to obtain resources for transmitting, the D2D UE sends the buffer status report (BSR) to an evolved node b (eNodeB) (or simply eNB or base station), wherein the Buffer status report (BSR) indicates the buffer size and D2D Layer 2 Group Identity. The eNodeB allocates resources to D2D UE based on the received BSR. The D2D Layer 2 Group ID in the BSR can be used by the eNodeB to provide resources to D2D UE from the resource pool corresponding to the group identified by D2D Layer 2 Group ID. The D2D Layer 2 Group ID in the BSR can also be used by the eNodeB to identify multiple transmissions to the same group by different D2D UEs and then the eNodeB can allocate distinct resources in the time domain to those D2D UEs. For example, D2D UE 1 sends BSR1 with D2D Layer 2 Group ID 1, D2D UE 2 sends BSR 2 with D2D Layer 2 Group ID 1. Since the resources requested by D2D UE1 and D2D UE2 are for the transmission to the same group, the eNodeB allocates separate resources in the time domain to both the D2D UE1 and the D2D UE2. Since D2D communication is half duplex, allocating separate resources in the time domain to D2D UE 1 and D2D UE2 will allow the D2D UE1 and D2D UE2 to receive each other's transmission.
Further, each group is assigned with a D2D Layer 2 Group ID with a size of 24 bits or 48 bits. Sending the D2D Layer 2 Group ID in BSR increases the BSR overhead significantly.
In view of the foregoing, there exists a need to provide a method and system to reduce the signaling overhead of sending the D2D Layer 2 Group ID during D2D communication.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.